This invention refers to developed improvement of an elevated track, to support and serve as a duct for a pneumatic propulsion system for transportation vehicles, for cargo or passengers.
The patent BR PI 7703372-8, requested by the same inventor in May 25, 1977, describes an elevated track to support and pneumatically propel a transportation vehicle, the ends of that track being supported on pillars. The track is built of reinforced concrete and has a hollow transversal section with an upper slot for the passage of a vertical rod originating from the transportation vehicle.
The patents BR PI 8301706-2, BR PI 8503504-1 and BR PI 9502056-0, requested by the same inventor in Apr. 4, 1983, Jul. 19, 1985 and May 11, 1995, respectively, describe an elevated track built in reinforced concrete which have the same general concept described in the earlier document.
This track when produced in reinforced concrete has a high implementation cost, especially because of the need for deep foundations. Due to the heavy weight of the concrete track its construction is slow and demands high capacity lifting equipment, even when using tracks made of precast, pre-stressed concrete. Due to these factors the project and transportation line construction offers little flexibility.
On the other hand, the patent BR PI 7906255-5, requested by the same inventor in Sep. 28, 1979, describes a track built of steel plate in a rectangular section tube shape with an upper slot, which is called the propulsion duct. This duct has joining flanges and reinforced at regular intervals, through where the track is supported on sustaining pillars. The vehicle moves using wheels with a special format which roll on a pair of cylindrical rails. The rails are farther apart than the duct width, being in balance and being fastened through the supports joined to the flanges and to the propulsion duct.
Due to its shape, conception and construction the metallic track has the following disadvantages:                it has a fragile aspect, because the propulsion duct is narrow and the vehicle wheels are supported on balancing rails which are fastened to spaced supports;        it has a small distance between the pillars, because the duct has a low rigidity and the vehicle has a heavy weight when loaded;        it needs a side protective structure, not foreseen in the earlier track;        it needs a side structure to access the track, for maintenance or passenger evacuation of the vehicle when it breaks down between stations, not foreseen in the earlier track.        